1. Field of the Invention
The present invention relates to the field of high speed digital circuits, in particular, high speed digital circuits based on CMOS technology. More specifically, the present invention relates to a method and apparatus for synchronizing periodic sync pulse generations by multiple remote high speed digital circuits in a digital system, such as a data instrumentation system.
2. Background
In a number of digital applications, such as data instrumentation, it is often necessary for multiple interrelated high speed circuits to generate synchronization signals to enable another circuit to synchronize certain processing. These circuits include but not limited to those operating at a speed of 66 MHZ or higher. A particular example is when a stream of data is being decomposed and sent in the form of multiple interrelated streams of data slices from a number of remote high speed circuits to a high speed acquisition circuit. More specifically, when each stream of data slices is sent with its own clock to allow the high speed acquisition circuit to capture the data from the interrelated streams of data slices. Since the different streams may encounter different analog delays in the system as they travel from the remote high speed circuits to the high speed acquisition circuit, the high speed acquisition circuit must be able to propedy capture the data from corresponding data slices in the interrelated streams. One approach is for each of the remote high speed circuits to send an additional series of periodic sync pulses having the same predetermined periodicity, each generated at the same input clock edge, thereby allowing the high speed acquisition circuit to discern the correspondence of the data slices in the different streams. For further description of using periodic sync pulses to synchronize data slices with variable skews, see copending U.S. patent application Ser. No. 08/040,902, entitled Method and Apparatus For Resychronizing Data Slices With Variable Skews, assigned to assignee of the present invention, which is hereby fully incorporated by reference.
However, it remains necessary for the the various series of periodic sync pulses to be generated in a synchronized manner. Thus, it is desirable to be able to synchronize the periodic sync pulse generations by multiple remote high speed circuits. As will be disclosed, the present invention provides such a method and apparatus, which advantageously achieves the desirable results. As will be obvious from the descriptions to follow, the present invention has particular application to high speed data instrumentation systems.